Compact medium access control (MAC) layer

ABSTRACT

Electronic devices having compactly designed media access control (MAC) layers, that can be employed as nodes in a wireless network such as an Institute of Electrical and Electronic Engineers&#39; (IEEE) 802.11 wireless local area network (WLAN) are described herein.

TECHNICAL FIELD

Embodiments of the invention relate generally to the field of electronicdevices, and more particularly, to the medium access control (MAC)layers of electronic devices that may be employed in a wireless localarea network (WLAN).

BACKGROUND

Wireless local area networks (WLAN) are becoming prevalent in manyenvironments. To facilitate implementation of WLAN, the Institute ofElectrical and Electronic Engineers (IEEE) has developed standards andprotocols for such networks. These standards are commonly referred to asthe IEEE 802.11 standards (802.11a, 802.11b, and so forth). To improveQuality of Service (QoS) for different applications working overWireless LAN, including voice and video transmission, the 802.11 estandard has been developed.

An 802.11 WLAN network is typically made up of a group of nodes forminga cell called Basic Service Set (BSS). A node may be an access point(AP) or a station (STA). When the WLAN is operating under the 802.11 estandard, the access point (AP) and the station (STA) are typicallyreferred to as QAP and QSTA. A QAP is usually physically coupled to awired network such as a local area network (LAN). The QAP within an802.11e WLAN cell will further be in wireless communication with one ormore STAs. In such a cell, there is typically only a single wirelessmedium or channel (e.g., band) that can be used for communicatingbetween the nodes.

The IEEE 802.11e standard is a protocol that defines methods to provideQoS service over WLAN for variety of applications including video- andaudio-type applications. Further, the 802.11e standard is based on twoprimary mechanisms for channel access.

The first mechanism is the Enhanced Distributed Channel Access (EDCA)protocol, which is a contention-based mechanism employing a contentionwindow (CW) method with random backoff to determine which node within acell has the right to transmit signals. That is, when EDCA is employed,the various nodes of a cell will compete during a specific time period(i.e., contention window) to determine which node(s) is/are permitted totransmit signals.

The second mechanism is the Hybrid Coordination Function (HCF)Controlled Channel Access (HCCA) protocol, which originates from thelegacy Point Coordination Function (PCF). The HCCA mechanism isbasically a polling-based protocol whereby a QAP polls each QSTA withinits cell whether or not each of the QSTAs wishes to transmit data(signals) and if so, to allocate an increment of time to transmit thedata. The time period assigned to a node for transmitting data (i.e.,signals) may be referred to as the “transmission opportunity” (TxOP).

Prior art nodes have resorted to complicated and/or inefficientarchitectures to concurrently support the two mechanisms (EDCA andHCCA).

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example and notby way of limitation in the figures of the accompanying drawings, inwhich like references indicate similar elements and in which:

FIG. 1 illustrates a portion of a compactly designed medium accesscontrol (MAC) layer of an electronic device, in accordance with someembodiments;

FIG. 2 illustrates a portion of a compactly designed medium accesscontrol (MAC) layer of an electronic device, in accordance with someother embodiments;

FIG. 3 illustrates a portion of a compactly designed medium accesscontrol (MAC) layer, in accordance with still some other embodiments;and

FIG. 4 is a block diagram of an example node, incorporated with theteachings of the invention, in accordance with some embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Illustrative embodiments of the present invention include compactarchitecture for Media Access Controller for electronic devices that maybe employed in wireless environments such as a WLAN employing the802.11e standard.

Various aspects of the illustrative embodiments will be described usingterms commonly employed by those skilled in the art to convey thesubstance of their work to others skilled in the art. However, it willbe apparent to those skilled in the art that alternate embodiments maybe practiced with only some of the described aspects. For purposes ofexplanation, specific materials and configurations are set forth inorder to provide a thorough understanding of the illustrativeembodiments. However, it will be apparent to one skilled in the art thatalternate embodiments may be practiced without the specific details. Inother instances, well-known features are omitted or simplified in ordernot to obscure the illustrative embodiments.

Further, various operations will be described as multiple discreteoperations, in turn, in a manner that is most helpful in understandingthe present invention; however, the order of description should not beconstrued as to imply that these operations are necessarily orderdependent. In particular, these operations need not be performed in theorder of presentation.

FIG. 1 depicts a portion of a more compactly designed medium accesscontrol (MAC) layer of an electronic device, in accordance with someembodiments. For purposes of this description, the compactly designedMAC layer may be referred to as Compact Distributed Channel Access(CDCA) MAC layer. The electronic device, which may communicatewirelessly or through a wired or optical medium, may be employed as anode (either QAP or QSTA) of a WLAN employing the 802.11e standard. Insome embodiments, the electronic device may be a wireless device. Inparticular, FIG. 1 shows an originator 106 of the MAC layer 104 of theelectronic device, the originator 106 being the originator of trafficstream. FIG. 1 also depicts a responder 108, which too will be discussedbelow. The MAC layer 104 may be above a physical (PHY) layer 103. Invarious embodiments, the originator 106 has a reduced number oftransmission queues (“queues”) relative to prior art originators. Asbriefly described above, at least a portion of the MAC layer 104 mayinclude both an originator 106 and a responder 108; however, thefollowing discussion relating to the various embodiments of theinvention will focus primarily on the design of the originator 106.

On the originator side of the MAC layer 104, MAC service data units(MSDUs) that include either traffic ID (TID) or traffic service ID(TSID) data depending on whether the MSDU is designated for EDCA or HCCAtransmission protocol may be received from an external source such asanother architectural layer (e.g., network layer) and initially receivedby a mapper 102, which may be part of the MAC layer 104. The mapper 102may receive the MSDUs and map the MSDUs to specific transmission queues(“queues” or “Tx queues”) 110 to 116. However, unlike prior artoriginators, all packets of the same user priority (UP) may use the sameChannel Access Method such as HCCA or EDCA. This allows for asignificant reduction in the number of Tx queues. Note that in otherembodiments, there may be fewer or more queues. The number (N) of queues110 to 116 in this illustration corresponds to the number of accesscategories associated with the electronic device (e.g., node of a WLAN).In this case, the access categories includes voice, video, best effort,and background. Each of these queues 110 to 116 may be furtherconfigured for traffic specification (TSPEC) thus accommodating MSDUsdesignated for either EDCA or HCCA transmission protocols. This mayallow the originator 106 to maintain fewer queues than typical prior artoriginators. As described before, each of the queues 110 to 116 maystore MSDUs designated for EDCA or HCCA transmission protocols.

For purposes of this description, the number of queues that accommodatesMSDUs to be transmitted using a first transmission protocol (e.g., EDCAtransmission protocol) may be referred to as n₁ while the number ofqueues that accommodates MSDUs to be transmitted using a secondtransmission protocol (e.g., HCCA transmission protocol) may be referredto as n₂. Of course, it is possible that in other embodiments, there maybe one or more transmission queues that accommodates MSDUs to betransmitted using a third, a fourth, and the like, transmissionprotocols (e.g., n₃, n₄, and so fourth).

According to some embodiments, the four queues 110 to 116 may becommunicatively coupled to a first channel access control unit 118 (notethat in other embodiments, the queues 110 to 116 may be coupled to morethan a single channel access control unit—see FIGS. 2 and 3, forexample), which in this case, is “per queue HCCA polling translator.”The four queues 110 to 116 may be further communicatively coupledindirectly through the first channel access control unit 118 to secondchannel access control units 120 to 126.

In this case, the first channel access control unit 118 may control anMSDU's access to a first wireless channel that may be based on HCCAprotocol while the second channel access control units 120 to 126 maycontrol an MSDU's access to a second wireless channel based on EDCAprotocol. Once an MSDU is directed by a first and/or a second channelaccess control unit[s] to get access to a first or a second channel, theMSDU is passed to an aggregation machine 128 which may aggregate anumber of frames into a block of frames. Then the block of frames may betransmitted to the physical (PHY) layer 103. As a result of theoriginator configuration described above, block acknowledgements (BAs)may be defined per transmission queues, thus allowing maintenance ofsingle sequencing number and single reordering buffer per queueaccordingly to block acknowledgement rules.

As for the responder 108 of the MAC layer 104 depicted in FIG. 1, forthe embodiments, the responder configuration includes a deaggregationmachine 130, a plurality of buffers 132 to 138, and a mapper 140,similar to other conventional responders. Thus, no further discussionwill be presented. Likewise, in the following discussion of the twoother embodiments depicted in FIGS. 2 and 3, the responder of thecompactly designed MAC layer 200 and 300 are also conventionallyconstituted. However, in alternate embodiments, the responder may alsobe more compactly designed as the originator. The responder 108 mayreceive various data in the form of electronic signals from otherelectronic devices (e.g., QSTAs and QAP of a WLAN) including, forexample, individual acknowledgements and block acknowledgements (BAs)transmitted by the other electronic devices.

FIG. 2 depicts at least a portion of a compactly designed MAC layer ofan electronic device in accordance with some embodiments. Again, as withthe electronic device of FIG. 1, the electronic device in thisillustration may be employed as a node (either QAP or QSTA) of a WLANemploying the 802.11 e standard. The MAC layer 200 may include anoriginator 202 and a responder 204 (the responder here has the sameconfiguration as the responder 108 of FIG. 1). As before, the originator202 may receive MSDUs (TID or TSID) from an external source such as thenetwork layer. When the MSDUs arrive at the MAC layer 200, they may beinitially received by a mapper 102, which maps the MSDUs to one or moretransmission queues 206 to 212.

As in the case before (i.e., FIG. 1), there are four transmission queues(“queues”) 206 to 212 that may be associated with four access categories(ACs), vocal, video, best effort, and background. Further, the queues206 to 212 may be communicatively coupled to channel access controlunits 214 to 218. However, unlike the originator 106 depicted in FIG. 1,only two of the queues 206 and 208 may store MSDUs designated fortransmission under the HCCA protocol (as indicated by TSID_x) while theother two queues 210 and 212 may store MSDUs designated for transmissionunder the EDCA protocol. As a result, unlike the originator 106 of FIG.1, only the first two queues 206 and 208, which may accommodate vocaland video MSDUs, are communicatively coupled only to the first channelaccess control unit 214 (n₁=2, as defined here, n_(x) refers to thenumber of queues coupled to specific channel access control unit[s]dedicated to protocol “x”). The other two queues 210 and 212, whichaccommodate best effort and background MSDUs are directlycommunicatively coupled to the second channel access control units 216and 218 (n₂=2). Again, as in the previous originator 106 depicted inFIG. 1, the first channel access control unit 214 may be the “per queueHCCA polling translator.” However, unlike the originator 106 depicted inFIG. 1, the first channel access control unit 214 may not be coupled inseries to second channel access control units 216 and 218. Instead, asdescribed above, the second channel access control units 216 and 218 maybe directly communicatively coupled to the other two queues 210 and 212.

Similar in some aspects to the originator 106 of FIG. 1, the first andsecond channel access control units 214 to 218 may control an MSDU'saccess to a first and/or a second channel. The first and second accesscontrol units 214 to 218 are further communicatively coupled to anaggregation machine 128. The MSDUs traveling through the originator 202may be directed by the first and second access control units 214 to 218to the aggregation machine 128 where frames may be aggregated to formone or more blocks. The aggregation machine 128 is furthercommunicatively coupled to the physical (PHY) layer 103. Whenappropriate, the one or more transmission blocks that may be formed bythe aggregation machine 128 may be sent to the PHY layer 103.

FIG. 3 depicts at least a portion of a compactly designed MAC layer 300of an electronic device in accordance with some embodiments. Again, aswith the electronic devices of FIGS. 1 and 2, the electronic device inthis illustration may be employed as a node (either QAP or QSTA) of an802.11 e WLAN. For the embodiments, FIG. 3 depicts a responder 304similar to the responders 108 and 204 of FIGS. 1 and 2. The originator302 depicted here, on the other hand, although similar to the originator202 depicted in FIG. 2, is configured slightly different. That is, inaddition to having a similar configuration and components, theoriginator 302, in this case, includes an extra second channel accesscontrol unit 306 that is communicatively coupled to the transmissionqueue 206 that may store vocal MSDUs. The extra second channel accesscontrol unit 306 further bypasses the first channel access control unit214 and is in direct communication with the aggregation machine 128.This allows a voice MSDU stored in the transmission queue 206 to betransmitted via HCCA or EDCA protocols. Transmission via EDCA protocolinstead of the HCCA protocol via the second channel access control unit306 may occur, for example, in the case of a missed QoS-poll.

FIG. 4 depicts a system having a compactly designed MAC layer thatincludes an originator and/or a responder such as those described above.In various embodiments, the system 400 may include a microprocessor 402,an interconnection 404 such as a bus, temporary memory 406 including,for example, SRAM and DRAM, a nonvolatile memory 410, a networkinterface 412, and an antenna 414. The compactly designed MAC layer thatincludes an originator and/or responder described above may be embodiedin the network interface 412. The network interface 412 and antenna 414may be used to communicate with other nodes of a wireless network suchas an 802.11 wireless local area network (WLAN).

In various embodiments, the antenna 414 may be a substantiallyomnidirectional antenna. In yet other embodiments, one or moresubstantially omnidirectional antenna(e) may be employed instead of thesingle antenna 414 depicted in FIG. 4. When multiple antennae are used,they may be used such that the system 400 has multiple input multipleoutput (MIMO) capabilities.

Accordingly, a compactly designed MAC layer suitable for use inelectronic devices of a WLAN has been described. Although the presentinvention has been described in terms of the above-illustratedembodiments, it will be appreciated by those of ordinary skill in theart that a wide variety of alternate and/or equivalent implementationscalculated to achieve the same purposes may be substituted for thespecific embodiments shown and described without departing from thescope of the present invention. Those of ordinary skill in the art willreadily appreciate that the present invention may be implemented in avery wide variety of embodiments. This description therefore is intendedto be regarded as illustrative instead of restrictive on embodiments ofthe present invention.

1. An apparatus, comprising: N queues to store MAC service data units(MSDUs), where N is an integer; a mapper coupled to the N queues to mapand store MSDUs into the N queues; one or more channel access controlunits of a first type, correspondingly coupled to n₁ of the N queues tocorrespondingly access one or more channels for the MSDUs stored in then₁ queue(s), for transmission in accordance with a first transmissionprotocol, where n₁ is an integer smaller or equal to N; and one or morechannel access control units of a second type, correspondingly coupledto n₂ of N queues to correspondingly access one or more channels for theMSDUs stored in the n₂ queue(s), for transmission in accordance with asecond transmission protocol, where n₂ is an integer smaller or equal toN, and at least a first of the N queues is a member of the n₁ queue(s),as well as a member of the n₂ queue(s).
 2. The apparatus of claim 1,wherein N equals a number of access categories supported under the firsttransmission protocol.
 3. The apparatus of claim 2, wherein n₁ equals N.4. The apparatus of claim 3, wherein the first transmission protocol iscompatible or in compliance with an enhanced distributed channel access(EDCA) protocol of an Institute of Electrical and Electronic Engineers(IEEE) 802.11e standard.
 5. The apparatus of claim 3, where n₁ and Nboth equal
 4. 6. The apparatus of claim 5, where n₂ and N both equal 4.7. The apparatus of claim 2, wherein n₂ equals N.
 8. The apparatus ofclaim 7, wherein the mapper is further designed to map and store videomedium access control (MAC) service data units (MSDUs) in a second ofthe N queues, that is a member of the n₁ queue, as well as a member ofthe n₂ queue.
 9. The apparatus of claim 1, wherein the mapper isdesigned to map and store voice medium access control (MAC) service dataunits (MSDUs) in said first of the N queues, that is a member of the n₁queue, as well as a member of the n₂ queue.
 10. An apparatus,comprising: N queues to store MAC service data units (MSDUs), where N isan integer, equal to or less than a number of access categoriessupported under a first transmission protocol; a mapper coupled to the Nqueues, to map and store MSDUs into the N queues; n₁ channel accesscontrol unit[s] of a first type, correspondingly coupled to n₁ of the Nqueues to access channels for MSDUs stored in the n₁ queues, fortransmission in accordance with the first transmission protocol, wheren₁ is an integer, smaller than or equal to N; and a channel accesscontrol unit of a second type coupled to n₂ of the N queues to accesschannels for MSDUs stored in the n₂ queues, for transmission inaccordance with a second transmission protocol, where n₂ is an integer,smaller than or equal to N.
 11. The apparatus of claim 10, whereineither n₁ or n₂ equals N.
 12. The apparatus of claim 10, wherein n₁ andN both equal
 4. 13. The apparatus of claim 10, wherein n₂ and N bothequal
 4. 14. The apparatus of claim 13, wherein the mapper is furtherdesigned to map and store video medium access control (MAC) service dataunits (MSDUs) in a second of the N queues that is a member of the n₁queue(s), as well as a member of the n₂ queue(s).
 15. The apparatus ofclaim 10, wherein the mapper is designed to map and store voice mediumaccess control (MAC) service data units (MSDUs) in said first of the Nqueues that is a member of the n₁ queue(s), as well as a member of then₂ queue(s).
 16. A method, comprising: mapping and storing a firstmedium access control (MAC) service data unit (MSDU) into a first queueof a MAC layer; first determining whether a first channel is availablefor transmission of the first MSDU stored in the first queue, inaccordance with a first transmission protocol; second determiningwhether a second channel is available for transmission of the first MSDUstored in the first queue, in accordance with a second transmissionprotocol; and conditionally outputting the first MSDU from the firstqueue to a physical layer for transmission, based at least in part onthe results of said first and second determining.
 17. The method ofclaim 16, further comprising: mapping and storing a second medium accesscontrol (MAC) service data unit (MSDU) into a second queue of the MAClayer; third determining whether a third channel is available fortransmission of the second MSDU stored in the second queue, inaccordance with the first transmission protocol; and conditionallyoutputting the second MSDU from the second queue to the physical layerfor transmission, based at least in part on the result of said thirddetermining.
 18. The method of claim 16, further comprising: mapping andstoring a second medium access control (MAC) service data unit (MSDU)into a second queue of the MAC layer; third determining whether a thirdchannel is available for transmission of the second MSDU stored in thesecond queue, in accordance with the second transmission protocol; andconditionally outputting the second MSDU from the second MSDU queue tothe physical layer for transmission, based at least in part on theresult of said third determining.
 19. The method of claim of claim 16,further comprising receiving an acknowledgement in response to theoutputted first medium access control (MAC) service data unit (MSDU).20. A system, comprising: a network interface having a medium accesscontrol (MAC) layer including N queues to store MAC service data units(MSDUs), where N is an integer, a mapper coupled to the N queues, to mapand store the MSDUs into the N queues, n₁ channel access control unit(s)of a first type, correspondingly coupled to n₁ of the N queues tocorrespondingly access channel(s) for the MSDUs stored in the n₁queue(s), for transmission in accordance with a first transmissionprotocol, where n₁ is an integer smaller than or equal to N, and achannel access control unit of a second type, coupled to n₂ of N queuesto access channels for the MSDUs stored in the n₂ queue(s), fortransmission in accordance with a second transmission protocol, where n₂is an integer smaller or equal to N, and at least a first of the Nqueues is a member of the n₁ queue(s), as well as a member of the n₂queue(s); a physical (PHY) layer coupled to the MAC layer; and one ormore substantially omnidirectional antenna(e) coupled to the physicallayer of the network interface.
 21. The system of claim 20, wherein Nequals a number of access categories supported under the firsttransmission protocol.
 22. The system of claim 20, wherein the mapper ofthe medium access control (MAC) layer is to map and store voice MACservice data units (MSDUs) in said first of the N queues, that is amember of the n₁ queue(s), as well as a member of the n₂ queue(s). 23.The system of claim 20, wherein the mapper of the medium access control(MAC) layer is further to map and store video MAC service data units(MSDUs) in a second of the N queues, that is a member of the n₁queue(s), as well as a member of the n₂ queue(s).
 24. An article,comprising: a storage medium; and instructions stored in the storagemedium, designed to enable an apparatus to practice the method of claim16.